Roman Abramovich had been missing at the Camp Nou, the oligarch absent as Chelsea so defied the odds to eliminate Barcelona and progress to the Champions League final. Yet, restored to his private box high in the west stand here, he still ended his week being treated to something exceptional. The high-fives clapped with those guests sharing the plush seats signified the moment Fernando Torres, the £50m forward turned folly, came good.

The locals had long been waiting for the Torres who had scorched defences during his time at Liverpool to revel in a Chelsea shirt. Now they may just believe that the forward, for all his travails since swapping Anfield for Stamford Bridge 15 months ago, has found form at the ideal moment. This team might have competed more coherently for the Premier League had the 28-year-old been this incisive all term. They could still claim the European Cup and FA Cup if the striker can summon displays this blistering from now on in.

Victory here thrust Chelsea back into contention for a top-four finish, particularly with Newcastle to visit south-west London on Wednesday night, for all that it was achieved against opponents whose defending was so feeble as to invite a thrashing. Torres and his supply line, the sublime Juan Mata principal among them, felt like flat track bullies with this a mismatch from the moment the visitors were breached in the opening 45 seconds. Chelsea had not previously won a league derby this season. They broke that duck by registering their best ever victory over these local rivals.

QPR teeter on the brink, though Chelsea will hardly care. This team's momentum builds with every contest, the squad inspired as players compete for places in two cup final lineups. The lack of a fit and available centre-half to partner John Terry went unnoticed as José Bosingwa stepped in adeptly.

In the latter stages, Sam Hutchinson was even granted his first senior appearance in two years – since when he has retired through injury and returned to the game – with the home crowd a permanent hubbub of celebration, even if their greatest acclaim was reserved for Torres. This was his first hat-trick since September 2009, the confidence of old visibly flooding back with each skip into space beyond dawdling defenders. Mata supplied him early possession and he delighted in his compatriot's delivery, yet QPR were so porous that the forward was supplied from all angles. Salomon Kalou's delicious angled pass, cutting out Taye Taiwo and Clint Hill, set the tone with Torres collecting, gliding round Paddy Kenny and finishing with calm authority. This was the instinctive Torres of a few years ago, rather than the player who had rather fretted at times when sent clear wearing Chelsea blue.

He was irrepressible thereafter, slamming in his side's fourth in the opening 25 minutes after Nedum Onuoha had headed against Kenny with the ball squirming loose. Chances had been passed up before Mata liberated the striker just after the hour- mark, the finish precise inside the far post to complete the treble. Abramovich's reaction was replicated all around the ground while the QPR players hung their heads.

Their lack of any defensive discipline had made this humiliation inevitable. A sixth successive away defeat – they have not prevailed on their travels since November – has left them precarious again. Even if they beat Stoke at Loftus Road on Sunday 6 May, they may need to pluck some kind of reward from Manchester City on the season's final afternoon. That already feels unlikely. They were prised apart at will. Daniel Sturridge had curled the hosts ahead in the opening minute, Kenny perhaps unsighted by Frank Lampard, with the substitute Florent Malouda registering the sixth. Djibril Cissé's consolation went almost unnoticed amid the glut.

Lost, too, was the reward chiselled by Terry in the game's opening exchanges. He had crunched a header beyond Kenny to extend Chelsea's early lead, the captain duly trotting off to the corner flag to pat, rather than thump, the badge on his chest and offer his hands out to the crowd as if accepting he had done wrong.

The apologetic reaction was for his dismissal in midweek, an idiotic red card that will cost him his place in Munich. He had used his programme notes to express a sense of regret. "I'm big enough to come out and man up when I make a mistake and, clearly, I made a mistake," he wrote.

Other issues clouded this occasion, chiefly the reality that Terry went face to face with Anton Ferdinand again here with his trial for allegedly racially abusing the QPR defender due to take place in July. There were boos from each set of fans for the opposition's centre-back over the course of the match, and the only visitors to shake Terry's hand were Joey Barton at the toss and the coach Marc Bircham in the aftermath. By then, the retreating captain could be satisfied in victory. For QPR, the ramifications of a horrible defeat are more troubling.

I love Torres, he deserved these 3 goals and couldn't have being any happier watching them go in, all he needed was players to pass him through balls, his runs were great and finished them well! I loved it, the first goal was best and 2nd was deserved he was in right spot to hit it in and was nice, the 3rd was just great run and finish! I wish he would have gotten more chances like this and glad the players passed to him in that game, he looked confident and wanting to shoot which was nice! I hope he starts a few of remaining games and even in the Cup games, should be great :)